Nonsensical error message when using a variable named eval in the same scope as a usage of eval

[Oliver Hunt]

Given this exciting function:
function f() { let eval=eval; print(a)}

We get the error

Cannot access uninitialized variable

It appears that triggering this requires using a variable named eval, and also accessing eval in the same scope.

This is very clearly a P0 :D

[Radar WebKit Bug Importer]

<rdar://problem/79822761>